Offset printing apparatus having disposable dampening and inking means

ABSTRACT

In an offset printing press, disposable dampening and inking materials, supplied in premoistened and preinked form, are supported in an unrestrained manner by dampening and inking cylinders, respectively, and disposed between them and the plate cylinder to provide controlled dampening and inking of the pressplate.

United States Patent [72] Inventor Robert D. Bracket! 1,954,550 4/1934Weide 101/142 X Wakefield, Mass. 2,006,364 7/1935 Morse 101/348 X |21]Appl. No. 740,212 2,181,935 12/1939 Carroll 101/227 [221 Filed June26,1968 2547,47] 4/1951 Janke 101/218 X [45] Patented July 20,19712,713,304 7/1955 Thomas 101/117 [73] Assignee PolaroidCorporation2,782,712 2/1957 Claff et a1. 101/227 X Cambridge, Mass. 2,800,8557/1957 Claffet al. 101/148 2,913,980 11/1959 Lindemann 101/148 3,220,83711/1965 Land et al.... 101/455 X [54] OFFSET PRINTING APPARATUS HAVING3,242,554 6 Raym nd l /l4 X DISPOSABLE DAMPENING AND INKING MEANS3,273,224 /1966 Spicer 101/148 X 18 Claims, Drawing Figs. 1,687,01610/1928 Green 101/336 52 vs. C: 101/142, FOREIGN PATENTS 101/147,101/348, 101/227, lOI/367, 83/663, 993,084 5/1965 Great Britain 248/206mtg 1435 2, 11g 240,101 247 1,147,300 6/1957 France 83/9262 [51] lnt.CIB4lf7/04, B4l f7/24,B41f3l/34 Field ofSearch 101/142, 227, 226,224,147,148, 348, 349, 415.1,141,

[56] References Cited UNITED STATES PATENTS 1,383,531 7/1921 Craig101/227 UX 1,580,917 4/1926 Putt 83/342X I 54 ea a,

Primary Examiner-Robert E. Pulfrey Assistant Examiner-Clifiord D.Crowder Attorney-Brown and Mikulka ABSTRACT: In an offset printingpress, disposable dampening and inking materials, supplied inpremoistened and preinked form, are supported in an unrestrained mannerby dampening and inking cylinders, respectively, and disposed betweenthem and the plate cylindler to provide controlled dampening and inkingof the pressplate.

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51:01am, and M ATTORNEYS OFFSET PRINTING APPARATUS HAVING DISPOSABLEDAMPENING AND INKING MEANS The invention concerns an offset printingpress of simplified construction, adapted especially to the extremelyrapid provision of smallto-medium-quantity production runs" and to theemployment, as a printing or pressplate of a photographic paper" print.This type of pressplate, in the interest of maximum rapidity from cameraexposure to duplicate prints and from the aspect of superior tonalvalues, is advantageously produced from rapid-processing or so-calledself-developing film materials of the type manufactured by PolaroidCorporation, Cambridge, Massachusetts, U.S.A., having a very fast filmspeed and involving a diffusion transfer method if image formation. Theprint or pressplate is preferably mounted on a plate cylinder by asimple mounting clip or clamp. An inking cylinder releasably mounting adisposable sleeve coated with a premilled ink is employed. The inkingsleeves, each capable of producing as many as I or more prints, aresupplied in hermetically sealed capsules. The apparatus also embodies asupply means for a paper stock in roll form in conjunction with anautomatic sheet cutter.

An inking sleeve can be installed on the inking cylinder and anexhausted sleeve removed therefrom and replaced by another in a fewseconds. The apparatus is adapted to produce either black-and-white orfull-color prints, rendered in line or in halftone using one or morepressplates and precoated inking sleeves depending upon the subjectmatter.

Use of a print of the character above described as a printing plate willbe noted as providing several distinct advantages among which,importantly, are:

Utmost speed from picture-taking to duplication in quantity, that is, anability to run off duplicate copies of the print immediately followingthe photographic exposure using the aforesaid self-developing type offilm.

An avoidance of the many steps involved in having to make conventional,e.g., metallic, printing plates with marked savings in time, attendantequipment and expense.

The saving in time and equipment provided by incorporation in theapparatus of the preinked disposable inking sleeve components where,usually, a plurality of milling rolls, ink solutions or mixtures and aconsiderable period for rendering inks in a usable state are necessary.

The simplification and reduction in printing costs made possible byusing a paper stock in roll form in conjunction with a relativelysimple, automatic sheet cutter.

In accordance with the aforesaid considerations, objects of theinvention are to provide printing apparatus especially adapted torelatively small, rapid and economical production runs" of high qualityin line or half-tone to provide printing apparatus of the characterdescribed utilizing paper prints as printing plates, the prints beingproduced by materials and methods identified with Polaroid Corporation;to provide apparatus of the type stated wherein printing plates areproduced by self-developing film materials and are available for useimmediately following a photographic exposure; to provide apparatus ascharacterized embodying a preinked disposable inking sheath or sleevesupplied in a hermetic capsule; to provide apparatus as set forthwherein a removable and disposable dampening sleeve is included; toprovide inking and dampening sleeves as described which are adapted tomovement longitudinally of their mounting cylinders for providing freshfunctional surfaces; to provide apparatus of the structure definedadapted to utilize as a printing sheet material a paper stock in rollform, thereby simplifying the paper feeding system; to provide apparatusof the category stated which includes a novel automatic sheet cutter;and to provide apparatus of the character describedwhich is adapted toproduce both black-and-white and full-color prints.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the apparatus possessing theconstruction, combination of elements and arrangement of parts which areexemplified in the following detailed disclosure, and the scope of theapplication of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIG. I is a diagrammatic perspective view of the printing pressapparatus from the left side;

FIG. 2 is a diagrammatic perspective view of the printing pressapparatus from the right side;

FIG. 3 is a diagrammatic perspective view of the paper cutter;

FIG. 4 is a diagrammatic perspective view of a shaft for releasablymounting a cylinder of the printing press;

FIG. 5 is a fragmentary detail of the shaft of FIG. 4;

FIG. 6 is a diagrammatic side view of the principal elements of theprinting press apparatus;

FIG. 7 is a diagrammatic perspective view of the plate cylinder;

FIGS. 8 and 9 are diagrammatic perspective views of the inking anddampening cylinders and cooperating sleeves; and

FIG. I0 is a diagrammatic view, in cross section, of several printingplate structures especially adapted to incorporatio with the apparatus.

In FIG. I the offset printing apparatus 10 is shown from the left side.It includes a rigid U-shaped frame 12, composed of a metal such asaluminum or steel, between the upwardly extending arms or sides 12a ofwhich are mounted the several rotatable elements of the apparatus. Asmore fully shown in conjunction with FIG. 6, these rotatable elementsinclude the following: a dampening cylinder 14 resiliently surfaced at16 and having a removable dampening sleeve 18 composed of awater-absorbent material such as a blotting paper; a plate cylinder 20including a printing plate retaining clip 22 releasably clamping a paperpress plate 24; an inking cylinder 26 resiliently surfaced at 28 andhaving a removable inking sleeve 30 composed of a resilient materialsuch as rubber, neoprene or the like; a blanket or offset cylinder 32including a rubber cover or so-called blanket 34; an impression cylinder36; the relatively vertically disposed paper-advancing means 38 and 40,each including a pair of rubber-faced, frictionally engaging driving orpropelling wheels 42; a pair of vertically disposed paper-shearingelements in the form of rolls 44 and 46 having hardened metallic inserts48 and 50 with a tautened steel cutting wire 52 extending longitudinallyof the face of the lower insert; and a paper-supply roll 54 carrying acontinuous length of printing paper 56.

As shown more clearly in FIG. 2, the apparatus is driven by clockwiserotation of the counterweighted hand crank 58. A manual drive ispreferred because it is: suited to the relatively small printing runsintended and to minimum bulk, weight and cost factors. On the otherhand, an electric motor can be employed for the purpose. In response toturning of the handcrank 58, the several cylinders and rollers arerotated in directions indicated by the arrows, as provided by aplurality of intermeshing gears of by frictional contact of theirsurfacing components with one another or with the paper 56.

The gears, mounted at the tips of their respective shafts, arepreferably composed of a plastic material such as nylon and have pitchdiameters enabling a 1:1 ratio of functional diameters of the rotatableelements. The gears comprise a primary driving and paper-advancing orpropelling gear 62 located at the extremity of the handcrank shaft, afirst idler gear 66 en gaging gear 62, the blanket gear 68 engaged bygear 66, the pressplate gear 70 driven by gear 68, a second idler gear72 driven by gear 62 and driving the upper cutter-roll gear 74, and thelower cutter-roll gear 76 driven by gear 74. It will be noted that theaxes of the paper cutting rolls 44 and 46, while parallel to oneanother, are not parallel to those of the other principal rotatableelements but are disposed at an angle of 5 relative thereto for a reasonto be described below. Accordingly, the idler gear 72 is a bevel geartapering slightly outwardly and having an axis which extends in adirection intermediate of the angularly different axes, above mentioned,namely, at an angle of 2.5 with respect thereto.

Completing the structure shown in FIGS. I and 2, a manually actuatablerod-shaped cam element 78, overturned at its extremity in the form of alever 78a, underlies and is adapted to raise or lower the clip or clamp22 for, respectively, releasing or clamping the paper pressplate 24. Aninclined tray 80 is provided to collect and stack the individual printedsheets severed by the cutter rolls and ejected from the apparatus. Thetray includes an overturned base portion 80a at one extremity releasablyengaging the transverse rod 82. It is pivotally mounted on a supportcomponent 84 at its other extremity.

The dampening cylinder I4, inking cylinder 26 and blanket cylinder 32are mounted for rotation on the cam-type shafts 86, 88 and 90,respectively. These shafts, one of which is shown in detail in FIGS. 4and 5, extend transversely between the U-shaped frame members 12a, beingremovably mounted in apertures formed therein. An inner sleeve 92 of thecylinder is mounted on portions 864 of the shaft which are eccentricallydisposed relative to the portions 86b and 860 thereof. The shaftportions 861) and 860 are adapted to be releasably mounted in theapertures 94 of the upstanding main frame portions 12a. A circulargroove 86d is adapted to receive a retaining pin 96 fastened to theframe. A section 86c of the shaft is provided with a longitudinal slot862,. The shaft also includes an enlarged end portion 86g terminating ina handle 86h. ,The portion 863 is positioned within a ring 96 integralwith the frame portion 12a. A spring-biased hardened-steel ball 100 ismounted within the end portion 86g and provides a frictional contactwith the inner surface of ring 98 sufficient to hold the shaft at anyposition to which it has been rotated.

When the shaft 86 has been turned by manual actuation of the handle 86hso as to align the slot 86c, with the pin 96, the shaft can be insertedin or removed from its mounting apertures. The shaft is shown at lockedposition in FIG. by reason of the positioning of pin 96 in groove 86d.The eccentricity of shaft portions 86a upon which each cylinder sleeve92 is mounted permits a translational movement of the cylinder toward oraway from the plate cylinder responsive to turning of the handle 86h.The cylinders rotate about the stationary sleeves 92 on suitablebearings. The shafts of other of the rotatable elements may be assumedto be mounted in bearing inserts of the frame, e.g., inserts of phosphorbronze impregnated with a lubricant. A pair of yokelike limit stops I02and 104, pivotally attached to the frame members 120 at 106 and 108 andslightly spaced from the ends of the cylinders 14 and 26 determine thedegree to which the dampening and inking sleeves l8 and 30 can movelongitudinally of the cylinders during operation.

The cutter rolls 44 and 46 are shown in greater detail in FIG. 3. Aspreviously intimated, the axes of these rolls are not parallel to theaxes of other rotatable elements nor at 90 to the direction of movementof the paper 56 but are angularly disposed at 5 to the other axes. Thecutting wire 52 is so angularly disposed across the face of the metalinsert 50 that when the inserts 48 and 50 are brought together in facingrelation the wire extends at 5 to a plane which would include the axesof both cutter rolls 44 and 46 and parallel to the axes of the otherrotatable elements. This relative disposition of axes provides aneffective cutting structure in which the wire is forced into, compressesand severs the paper while involving a miminum of resistance to rotationof the cutter rolls. This is believed to be due to a distribution of thecutting force throughout a rotation of the cutter rolls which is greaterthan would be the case where the axes of both of the cutter rolls andthe cutting wire at 90 to the direction of movement of the paper 56.

The inking sleeve 30, illustrated in FIG. 8, is formed of a rubber,neoprene or other elastic material of a given resiliency. It is suppliedprecoated with a layer of a suitable lithographic ink Il0 composed, forexample, of chosen proportions of pigment, vehicle, drier and compoundsfor adjusting its working qualities. It is to be assumed that the inkhas previously undergone milling, kneading or other treatment ofa naturecomparable to that provided by the multiroll inking system ofaconventional printing press. Accordingly, the ink is to be regarded asof a correct consistency when coated on the sleeve 30. The thus-coatedsleeve 30 is provided in a hermetically sealed capsule I I I formed, forexample, of a plastic such as a polystyrene. When inserted in thecapsule, a cover element I12 is fitted thereto and a pressure-sensitivetape 114, having a noncoated tab 114:: for removal purposes, is boundaround the edge of the cover and contiguous portions of th capsule toprovide an airtight seal.

To install the inking sleeve, the guide 104 is pivoted upwardly to openposition, the shaft 88 is released and pulled outwardly, and the inkingcylinder 26 is lifted from the printing press. An inking sleeve 30 isremoved from its sealed capsule ii I and slipped over the inkingcylinder, after which the cylinder is remounted. Both the inking sleeveand capsule may be regarded as of a disposable category or the sleevemay again be inked and stored in the capsule for future use.

The moistening sleeve 18, shown in FIG. 9, is composed ofa paperlikematerial of a fibrous, porous and hygroscopic type such as a form ofblotting paper, surface-treated in an appropriate manner as for instanceby a resinous plastic substance, to a degree insufficient to offset itsabsorptive properties but to anchor its fibers against displacement. Thesleeve is preimpregnated with a suitable moistening solution, e.g., asolution of seven parts water to one part glycerin, and supplied in ahermetically sealed capsule of the type used for the inking sleeve anddescribed relative to FIG. 8. Opening of guide 102 and removal of themoistening cylinder 14 to install or remove the sleeve I8 areaccomplished in the manner previously explained. Both sleeves I8 and 20are adapted to a slight longitudinal movement on their respectivecylinders during a given printing run. This movement, to the extentpermitted by the guides I02 and I04, provides a varied source ofmoistening liquid and ink and is made possible by the somewhat loose fitof the sleeves, enhanced by a slight taper of their inner diameters.

Means for releasably and easily mounting the printing press on a flatsurface such as that of a table top are indicated in FIG. 2. Arectangular aperture 116 is formed in the base of the supporting frame12. The entire base, including the aperture H6, is covered on its lowersurface by a sheet I18 of a resilient material such as a rubber orneoprene which is bonded thereto. A rectangular metal plate 120, ofappreciably smaller dimensions than the aperture 6, is fastened to theinner (upper) surface of the sheet 118, as by the rivets 122. A yokelikecam-follower 124 is fixedly attached to the central portion of the uppersurface of plate 120. A rodlike cam element 126 is mounted in bearingmeans 128 of the base 12b of the supporting frame so as to extendtransversely thereacross, its camming portion 126a being adapted to bearagainst and force upwardly the cam-follower portion 124a in response tomanual rotation of the lever 130 which is fastened to an end of camelement 126. Upward movement of the cam follower also lifts the attachedplate and that portion of the resilient sheet I I8 fastened theretowithin the area of aperture 116, the sheet 118 stretching as required toprovide a concavity at the area I16 with respect to the remaining planarsheet portions. A vacuum is thus provided within the concavity whichserves to hold the printing press firmly against displacement on thetable top.

It will be noted that the paper pressplate 24 is attached by the clip 22to the plate cylinder 20 at one end only, namely, at that leading endwhich is drawn or pulled due to rotation of the cylinder in a givendirection. The trailing portions and opposite end of the pressplate arenot fastened to the cylinder and thus are allowed to assume anunhampered, natural and firm seating against the cylinder surface. Theplate cylinder, as well as the impression cylinder, are preferablycomposed of a metal such as aluminum.

The relative disposition and movement of the cylinders and otherrotatable elements is shown graphically in FIG. 6. It will be understoodthat the moistening sleeve 18 applies the moistening solution to thepaper pressplate 24 prior to application thereto of the printing ink 110by the inking sleeve 30. The frictionally surfaced propulsive wheels 42are of slightly larger diameter than that of the periphery of theblanket 34 and that of the impression cylinder 36 to insure a positiveforward movement of the sheet 56 in a flat slightly tautened condition.

Conventional printing inks and papers may be employed in conjunctionwith the pressplates, the preinked and premoistened sleeves, and otherelements of the apparatus, as described. An example of a suitableprinting paper is a socalled 70-pound offset enamel."

The printing apparatus, as above described, is adapted to the productionof either black-and-white or color prints rendered in line or inhalftone the latter in terms ofa screen of up to 150 lines or greater tothe inch. Where, for example, a full-color rendition is the objective,the cutter rolls would not initially be employed, roll 44 beingpivotally mounted by means, not shown, for bodily movement away fromroll 46, as indicated by the broken line 132. A first continuous lengthof the paper would be impressed from the blanket in the form of an imageby, for example, a red ink supplied by a red-ink precoated inking sleeve18 with. a color-separation paper pressplate representing the warm colorof the photographic subject. The continuous length of paper would be runsuccessively through the apparatus for providing correctly registeredgreen and blue color-separation images and possibly a light black image.With impression of the last image, the cutter would again befunctionally positioned. While the blanket is shown as permanentlyinstalled and subject to cleansing, it would be possible to utilizeseparate blanket sleeve for each color, of a cleansable or disposabletype.

Examples of paper pressplates of types contemplated in apparatus of thepresent invention are illustrated in FIG. 10. The lithographic type ofpressplate 134 of example a" includes a paper support 136 withprinting-ink-repellent and moisteningsolution-receptive areas 138, andprinting-ink-receptive areas 140 rendered in terms of an imagewisedeposition of silver. Example b" represents a functionally similarstructure 1340 wherein the imagewise silver deposition is slightlyraised with respect to the plane of the nonimage-carrying areas whichare approximately identified with the support to produce, in effect, arelief form of printing plate. As an example of a system for preparingpaper pressplates, mention may be made of that described and claimed inU.S. Pat. No. 3,220,837. In the ex ample c a somewhat differentstructure produced by a diffusion transfer method followed by asubsequent surface treatment is illustrated. The etched" form therebyprovided includes the hydrophilic or moistening-solution-receptive area142 and the indented oleophilic or printing-ink-receptive areas 144.

As previously intimated, the incorporation with the apparatus of paperpressplates of the type derived from a highspeed self-developing filmenables the production of a succession of duplicate prints of thehighest quality and capable of the widest possible range of contentimmediately following a photographic exposure. When a pressplate of thistype is combined with the minimum makeready characteristics of thepreinked inking sleeve and the premoistened moistening sleeve, theoverall production cycle is desirably simplified, extremely rapid andeconomical.

Since certain changes may be made in the above apparatus withoutdeparting from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What I claim is:

1. An offset printing apparatus adapted to effect the inking of apressplate and transfer of anink impression therefrom to printingmaterial for economically producing relatively small printing quantitieswith a minimum of makeready, said apparatus comprising: a supportingframe; a plate cylinder rotatably mounted on said frame, said platecylinder adapted to have a pressplate mounted thereon; means fordampening such pressplate after it is mounted on said plate cylinder; aninking cylinder rotatably mounted on said frame adjacent said platecylinder; means for rotating at least said plate cylinder; means forinking such pressplate after it is mounted on said plate cylinderincluding resilient sheet material supplied in precoated form with inkof correct printing consistency supported by said inking cylinder in anunrestrained manner so as to permit oscillatory motion of said precoatedsheet material with respect to the longitudinal axis of said inkingcylinder, said precoated sheet material being disposed between saidinking cylinder and said plate cylinder in pressure contact therebetweensuch that said precoated sheet material is repeatedly pressed againstsuch pressplate for repeated inking thereof and is driven longitudinallyof said inking cylinder for providing fresh functional surfaces to suchpressplate responsive to rotation of said plate cylinder; means forlimiting said movement of said precoated sheet material across saidinking cylinder; a blanket cylinder rotatably mounted on said frameadjoining said plate cylinder for removal of an ink impression of suchpressplate during each rotation of said plate cylinder; means forreceiving a supply of printing material; means for feeding such printingmaterial from such supply means past said blanket cylinder; and meansfor pressing such printing material against said blanket cylinder fortransferring an ink impression of such pressplate to such printingmaterial.

2. An offset printing apparatus, as defined in claim I, wherein saidpressplate is a paper print of a type formed by a diffusion transferprocess.

3. An offset printing apparatus, as defined in claim 2, wherein saidpaper print is ofa type formed from a high speed self-developing filmmaterial involving a deposition of silver on areas utilized for imageformation.

4. The offset printing apparatus of claim 1 wherein said limiting meanscomprise a pair of members disposed adjacent the edges of said sheetmaterial and spaced apart a distance slightly exceeding the lateraldimension thereof whereby a slight movement of said material with.respect to the longitudinal axis of said inking cylinder is permittedduring rotation of said plate cylinder 5. The offset printing apparatusofclaim l wherein said link ing cylinder is demountable and saidprecoated sheet material comprises a sleeve loosely fitted to saidinking cylinder and adapted to he slipped thereon.

6. The offset printing apparatus of claim 5 wherein said limiting meanscomprise a pair of members spaced apart a distance slightly exceedingthe longitudinal dimension of said sleeve which, in cooperation with theloose fit thereof, permit a slight longitudinal movement of said sleeveon its cylinder during operation rotation of the latter.

7. The offset printing apparatus of claim 5 wherein said limiting meanscomprise a yokelike member having an open end portion for providing apair of opposed members spaced apart a distance exceeding thelongitudinal dimension of said sleeve, and said yokelike member isdisplaceably mounted on said frame with its open end portion adjacentthe ends of said sleeve.

8. The offset printing apparatus of claim 5 including a pair of rolls,and a severing element in the form of a tautened wire extendinglengthwise across one of said rolls, said rolls rotatably mounted insaid frame at a small angle to said blanket cylinder, and said wiredisposed on said one roll at the same angle but opposite direction tothe mounting angle of said rolls such that said wire is substantiallyparallel to the axis of said blanket cylinder, and means for feedingsaid paper from said blanket cylinder between said severing rolls.

9. An offset printing apparatus, as defined in claim 5, wherein saidpreinked sleeve is composed of a resilient material and a layer ofprinting ink formed on its surface has been treated prior to itsapplication to said sleeve to assume a form completely adapted totransfer to said pressplate for printing purposes.

10. An offset printing apparatus adapted to effect the inking of apressplate and transfer of an ink impression therefrom to printingmaterial for economically producing relatively small printing quantitieswith a minimum of makeready, said apparatus comprising: a supportingframe having spaced apart upright members; a plurality of shaftssupported in apertures of said upright members and extended thereacross;a plate cylinder rotatably mounted on a first of said shafts, said platecylinder adapted to have a pressplate mounted thereon; an inkingcylinder rotatably mounted on a second of said shafts adjacent saidplate cylinder; means for rotating said plate cylinder; means for inkingsuch pressplate after it is mounted on said plate cylinder includingsheet material supplied in precoated form with ink of correct printingconsistency disposed between said inking cylinder and said platecylinder in pressure contact therebetween and supported by said inkingcylinder in an unrestrained manner so as to permit movement of saidsheet material with respect to the longitudinal axis of said inkingcylinder; said second shaft having a centrally located cylinder-supportportion eccentrically disposed relative to its end portions forproviding a translational motion of said inking cylinder toward or awayfrom said plate cylinder upon rotation of said second shaft, a springbiased member mounted in said second shaft at one end thereof andadapted to provide frictional contact between said second shaft and oneof said upright members so as to hold said shaft at any position towhich it is rotated; a retaining member displaceably mounted on one ofsaid upright members; and a circular groove disposed on said secondshaft and adapted to releasably receive said retaining member, therebyproviding for withdrawal of said inking cylinder shaft and removal ofsaid inking cylinder for replacement of said precoated sheet material.

ll. An offset printing apparatus adapted to effect the inking of apressplate and transfer of an ink impression therefrom to printingmaterial for economically producing relatively small printing quantitieswith a minimum of makeready, said apparatus comprising: a supportingframe; a plate cylinder rotatably mounted on said frame, said platecylinder adapted to have a pressplate mounted thereon; means for inkingsuch pressplate after it is mounted on said plate cylinder; a dampeningcylinder rotatably mounted on said frame adjacent said plate cylinder;means for rotating at least said plate cylinder; means for dampeningsuch pressplate after it is mounted on said plate cylinder includingsheet material supplied in premoistened form with moistening solution ofcorrect printing consistency supported by said dampening cylinder in anunrestrained manner so as to permit oscillatory motion of saidpremoistened sheet material with respect to the longitudinal axis ofsaid dampening cylinder, said premoistened sheet material being disposedbetween said dampening cylinder and said plate cylinder in pressurecontact therebetween such that said premoistened sheet material isrepeatedly pressed against such pressplate for repeated dampeningthereof and is driven longitudinally of said dampening cylinder forproviding fresh functional surfaces to such pressplate responsive torotation of said plate cylinder; means for limiting said movement ofsaid premoistened sheet material across said dampening cylinder; ablanket cylinder rotatably mounted on said frame adjoining said platecylinder for removal of an ink impression of such pressplate during eachrotation of said plate cylinder; means for receiving a supply ofprinting material; means for feeding such printing material from suchsupply means past said blanket cylinder; and means for pressing suchprinting material against said blanket cylinder for transferring an inkimpression of such pressplate to such printing material.

12. The offset printing apparatus of claim ll wherein said limitingmeans comprise a pair of members disposed adjacent the edges of saidsheet material and spaced apart a distance slightly exceeding thelateral dimension thereof whereby a slight movement of said materialwith respect to the longitudinal axis of said dampening cylinder ispermitted during rotation of said plate cylinder.

13. The offset printing apparatus of claim 11 wherein said dampeningcylinder is demountable and said premoistened sheet material comprises asleeve loosely fitted to said dampening cylinder and adapted to beslipped thereon.

14. The offset printing apparatus of claim 13 wherein said limitingmeans comprise a pair of members spaced apart a distance slightlyexceeding the longitudinal dimension of said sleeve which, incooperation with the loose fit thereof, permit a slight longitudinalmovement of said sleeve on its cylinder during operational rotation ofthe latter.

15. The offset printing apparatus of claim 13 wherein said limitingmeans comprise a yokelike member having an open end portion forproviding a pair of opposed members spaced apart a distance exceedingthe longitudinal dimension of said sleeve and said yokelike member isdisplaceably mounted on said frame with its open end portion adjacentthe ends of said sleeve.

16. An offset printing apparatus, as defined in claim 13, wherein saidpremoistened sleeve is composed of a fibrous, porous, hygroscopic,paperlike material pretreated to prevent displacement of its fibers.

17. An offset printing apparatus adapted to effect the the inking of apressplate and transfer of an ink impression therefrom to printingmaterial for economically producing relatively small printing quantitieswith a minimum of makeready, said apparatus comprising: a supportingframe; a plate cylinder rotatably mounted on said frame, said platecylinder adapted to have a pressplate mounted thereon; a dampeningcylinder rotatably mounted on said frame adjacent said plate cylinder;means for dampening such pressplate after it is mounted on said platecylinder including sheet material supplied in premoistened form withmoistening solution of correct printing consistency supported by saiddampening cylinder in an unrestrained manner so as to permit oscillatorymotion of said premoistened sheet material with respect to thelongitudinal axis of said dampening cylinder; an inking cylinderrotatably mounted on said frame adjacent said plate cylinder; means forinking such pressplate after it is mounted on said plate cylinderincluding resilient sheet material supplied in preinked form with ink ofcorrect printing consistency supported by said inking cylinder in anunrestrained manner so as to permit oscillatory motion of said precoatedsheet material with respect to the longitudinal axis of said inkingcylinder; said cylinders rotatably mounted in said frame with saidpremoistened and said precoated sheet material disposed between saidplate cylinder and said dampening and inking cylinders, respectively, inpressure contact therebetween such that said premoistened and saidprecoated sheet material are sequentially and repeatedly pressed againstsuch pressplate for repeated dampening and inking thereof and are drivenlongitudinally of their supporting cylinders for providing freshfunctional surfaces to such pressplate responsive to rotation of saidplate cylinder; means for limiting premoistened and said precoated sheetmaterial across their respective cylinders; a blanket cylinder rotatablymounted on said frame adjoining said plate cylinder for removal of anink impression of such pressplate during each rotation of said platecylinder; means for receiving a supply of printing material; means forfeeding such printing material from such supply means past said blanketcylinder; and means for pressing such printing material against saidblanket cylinder for transferring an ink impression of such pressplateto such printing material.

18. The offset printing apparatus of claim 33 wherein said dampening andinking cylinders are demountable and said sheet materials comprisesleeves loosely fitted to their respective cylinders and adapted to beslipped thereon, and said limiting means comprise a pair of membersdisposed adjacent the ends of each sleeve and spaced apart a distanceslightly exceeding the longitudinal dimension of each sleeve which, incooperation with the loose fit thereof, permit a slight longitudinalmovement of said sleeves on their cylinders during operational rotationof the latter.

1. An offset printing apparatus adapted to effect the inking of apressplate and transfer of an ink impression therefrom to printingmaterial for economically producing relatively small printing quantitieswith a minimum of makeready, said apparatus comprising: a supportingframe; a plate cylinder rotatably mounted on said frame, said platecylinder adapted to have a pressplate mounted thereon; means fordampening such pressplate after it is mounted on said plate cylinder; aninking cylinder rotatably mounted on said frame adjacent said platecylinder; means for rotating at least said plate cylinder; means forinking such pressplate after it is mounted on said plate cylinderincluding resilient sheet material supplied in precoated form with inkof correct printing consistency supported by said inking cylinder in anunrestrained manner so as to permit oscillatory motion of said precoatedsheet material with respect to the longitudinal axis of said inkingcylinder, said precoated sheet material being disposed between saidinking cylinder and said plate cylinder in pressure contact therebetweensuch that said precoated sheet material is repeatedly pressed againstsuch pressplate for repeated inking thereof and is driven longitudinallyof said inking cylinder for providing fresh functional sUrfaces to suchpressplate responsive to rotation of said plate cylinder; means forlimiting said movement of said precoated sheet material across saidinking cylinder; a blanket cylinder rotatably mounted on said frameadjoining said plate cylinder for removal of an ink impression of suchpressplate during each rotation of said plate cylinder; means forreceiving a supply of printing material; means for feeding such printingmaterial from such supply means past said blanket cylinder; and meansfor pressing such printing material against said blanket cylinder fortransferring an ink impression of such pressplate to such printingmaterial.
 2. An offset printing apparatus, as defined in claim 1,wherein said pressplate is a paper print of a type formed by a diffusiontransfer process.
 3. An offset printing apparatus, as defined in claim2, wherein said paper print is of a type formed from a high speedself-developing film material involving a deposition of silver on areasutilized for image formation.
 4. The offset printing apparatus of claim1 wherein said limiting means comprise a pair of members disposedadjacent the edges of said sheet material and spaced apart a distanceslightly exceeding the lateral dimension thereof whereby a slightmovement of said material with respect to the longitudinal axis of saidinking cylinder is permitted during rotation of said plate cylinder 5.The offset printing apparatus of claim 1 wherein said linking cylinderis demountable and said precoated sheet material comprises a sleeveloosely fitted to said inking cylinder and adapted to be slippedthereon.
 6. The offset printing apparatus of claim 5 wherein saidlimiting means comprise a pair of members spaced apart a distanceslightly exceeding the longitudinal dimension of said sleeve which, incooperation with the loose fit thereof, permit a slight longitudinalmovement of said sleeve on its cylinder during operation rotation of thelatter.
 7. The offset printing apparatus of claim 5 wherein saidlimiting means comprise a yokelike member having an open end portion forproviding a pair of opposed members spaced apart a distance exceedingthe longitudinal dimension of said sleeve, and said yokelike member isdisplaceably mounted on said frame with its open end portion adjacentthe ends of said sleeve.
 8. The offset printing apparatus of claim 5including a pair of rolls, and a severing element in the form of atautened wire extending lengthwise across one of said rolls, said rollsrotatably mounted in said frame at a small angle to said blanketcylinder, and said wire disposed on said one roll at the same angle butopposite direction to the mounting angle of said rolls such that saidwire is substantially parallel to the axis of said blanket cylinder, andmeans for feeding said paper from said blanket cylinder between saidsevering rolls.
 9. An offset printing apparatus, as defined in claim 5,wherein said preinked sleeve is composed of a resilient material and alayer of printing ink formed on its surface has been treated prior toits application to said sleeve to assume a form completely adapted totransfer to said pressplate for printing purposes.
 10. An offsetprinting apparatus adapted to effect the inking of a pressplate andtransfer of an ink impression therefrom to printing material foreconomically producing relatively small printing quantities with aminimum of makeready, said apparatus comprising: a supporting framehaving spaced apart upright members; a plurality of shafts supported inapertures of said upright members and extended thereacross; a platecylinder rotatably mounted on a first of said shafts, said platecylinder adapted to have a pressplate mounted thereon; an inkingcylinder rotatably mounted on a second of said shafts adjacent saidplate cylinder; means for rotating said plate cylinder; means for inkingsuch pressplate after it is mounted on said plate cylinder includingsheet material supplied in precoated form with ink of correct Printingconsistency disposed between said inking cylinder and said platecylinder in pressure contact therebetween and supported by said inkingcylinder in an unrestrained manner so as to permit movement of saidsheet material with respect to the longitudinal axis of said inkingcylinder; said second shaft having a centrally located cylinder-supportportion eccentrically disposed relative to its end portions forproviding a translational motion of said inking cylinder toward or awayfrom said plate cylinder upon rotation of said second shaft, a springbiased member mounted in said second shaft at one end thereof andadapted to provide frictional contact between said second shaft and oneof said upright members so as to hold said shaft at any position towhich it is rotated; a retaining member displaceably mounted on one ofsaid upright members; and a circular groove disposed on said secondshaft and adapted to releasably receive said retaining member, therebyproviding for withdrawal of said inking cylinder shaft and removal ofsaid inking cylinder for replacement of said precoated sheet material.11. An offset printing apparatus adapted to effect the inking of apressplate and transfer of an ink impression therefrom to printingmaterial for economically producing relatively small printing quantitieswith a minimum of makeready, said apparatus comprising: a supportingframe; a plate cylinder rotatably mounted on said frame, said platecylinder adapted to have a pressplate mounted thereon; means for inkingsuch pressplate after it is mounted on said plate cylinder; a dampeningcylinder rotatably mounted on said frame adjacent said plate cylinder;means for rotating at least said plate cylinder; means for dampeningsuch pressplate after it is mounted on said plate cylinder includingsheet material supplied in premoistened form with moistening solution ofcorrect printing consistency supported by said dampening cylinder in anunrestrained manner so as to permit oscillatory motion of saidpremoistened sheet material with respect to the longitudinal axis ofsaid dampening cylinder, said premoistened sheet material being disposedbetween said dampening cylinder and said plate cylinder in pressurecontact therebetween such that said premoistened sheet material isrepeatedly pressed against such pressplate for repeated dampeningthereof and is driven longitudinally of said dampening cylinder forproviding fresh functional surfaces to such pressplate responsive torotation of said plate cylinder; means for limiting said movement ofsaid premoistened sheet material across said dampening cylinder; ablanket cylinder rotatably mounted on said frame adjoining said platecylinder for removal of an ink impression of such pressplate during eachrotation of said plate cylinder; means for receiving a supply ofprinting material; means for feeding such printing material from suchsupply means past said blanket cylinder; and means for pressing suchprinting material against said blanket cylinder for transferring an inkimpression of such pressplate to such printing material.
 12. The offsetprinting apparatus of claim 11 wherein said limiting means comprise apair of members disposed adjacent the edges of said sheet material andspaced apart a distance slightly exceeding the lateral dimension thereofwhereby a slight movement of said material with respect to thelongitudinal axis of said dampening cylinder is permitted duringrotation of said plate cylinder.
 13. The offset printing apparatus ofclaim 11 wherein said dampening cylinder is demountable and saidpremoistened sheet material comprises a sleeve loosely fitted to saiddampening cylinder and adapted to be slipped thereon.
 14. The offsetprinting apparatus of claim 13 wherein said limiting means comprise apair of members spaced apart a distance slightly exceeding thelongitudinal dimension of said sleeve which, in cooperation with theloose fit thereof, permit a slight longitudinal movement of said sleeveon its cylinder durIng operational rotation of the latter.
 15. Theoffset printing apparatus of claim 13 wherein said limiting meanscomprise a yokelike member having an open end portion for providing apair of opposed members spaced apart a distance exceeding thelongitudinal dimension of said sleeve and said yokelike member isdisplaceably mounted on said frame with its open end portion adjacentthe ends of said sleeve.
 16. An offset printing apparatus, as defined inclaim 13, wherein said premoistened sleeve is composed of a fibrous,porous, hygroscopic, paperlike material pretreated to preventdisplacement of its fibers.
 17. An offset printing apparatus adapted toeffect the the inking of a pressplate and transfer of an ink impressiontherefrom to printing material for economically producing relativelysmall printing quantities with a minimum of makeready, said apparatuscomprising: a supporting frame; a plate cylinder rotatably mounted onsaid frame, said plate cylinder adapted to have a pressplate mountedthereon; a dampening cylinder rotatably mounted on said frame adjacentsaid plate cylinder; means for dampening such pressplate after it ismounted on said plate cylinder including sheet material supplied inpremoistened form with moistening solution of correct printingconsistency supported by said dampening cylinder in an unrestrainedmanner so as to permit oscillatory motion of said premoistened sheetmaterial with respect to the longitudinal axis of said dampeningcylinder; an inking cylinder rotatably mounted on said frame adjacentsaid plate cylinder; means for inking such pressplate after it ismounted on said plate cylinder including resilient sheet materialsupplied in preinked form with ink of correct printing consistencysupported by said inking cylinder in an unrestrained manner so as topermit oscillatory motion of said precoated sheet material with respectto the longitudinal axis of said inking cylinder; said cylindersrotatably mounted in said frame with said premoistened and saidprecoated sheet material disposed between said plate cylinder and saiddampening and inking cylinders, respectively, in pressure contacttherebetween such that said premoistened and said precoated sheetmaterial are sequentially and repeatedly pressed against such pressplatefor repeated dampening and inking thereof and are driven longitudinallyof their supporting cylinders for providing fresh functional surfaces tosuch pressplate responsive to rotation of said plate cylinder; means forlimiting premoistened and said precoated sheet material across theirrespective cylinders; a blanket cylinder rotatably mounted on said frameadjoining said plate cylinder for removal of an ink impression of suchpressplate during each rotation of said plate cylinder; means forreceiving a supply of printing material; means for feeding such printingmaterial from such supply means past said blanket cylinder; and meansfor pressing such printing material against said blanket cylinder fortransferring an ink impression of such pressplate to such printingmaterial.
 18. The offset printing apparatus of claim 33 wherein saiddampening and inking cylinders are demountable and said sheet materialscomprise sleeves loosely fitted to their respective cylinders andadapted to be slipped thereon, and said limiting means comprise a pairof members disposed adjacent the ends of each sleeve and spaced apart adistance slightly exceeding the longitudinal dimension of each sleevewhich, in cooperation with the loose fit thereof, permit a slightlongitudinal movement of said sleeves on their cylinders duringoperational rotation of the latter.